Resilient filaments



Patented Oct. 1, 194

' UNITED STATES PATENT *oF FicE I, 7 V f, tRE SILIENT FILAMENTS I 7 Frederick G. Dodge, La Vale, MtL, assignor to 001- l anese Corporation of America; a corporation of Delaware No Drawing. Application October 6,1943, Serial No. 505,165

ing a basis of cellulose acetate or other organic derivative of cellulose whereby said filaments may be permanently crimped. I Another object of my invention is to provide a process tor the treatment of cellulose acetate or other organic derivative of cellulose filamentary materials to render the latter more resilient and to impart thereto a voluminous structure.

, Other objects of myinvention will appear hereinafter from the followingdetailed description. Filaments having a basis of cellulose acetate or other organic derivative of cellulose in staple fiberform have been'found to possess excellent insulating characteristics when employed in the manufacture of comforters, sleeping bags and like articles. Continuous artificial filaments having a basis of cellulose acetate or other organic derivative of cellulose differ from materials such as cotton and wool in that the artificial filaments are relatively smooth. They do not possess a crimped or crinkled structure, such as that found in naturally, occurring fibers such as wool, which structure is largely responsible for the character istic hand or fullness of said materials. Consequently, when the ordinary artificial filaments having a basis of cellulose acetate or other organic derivative of cellulose are subjected to prolonged pressure, as, for example, in a sleeping bag, they tend to become matted and upon release of the pr'essure'do not fully return to their original voluminous state. This matting causes the dead air spaces in said artificial filamentary materials to be reduced in volume and the latter gradually lose some of their insulating properties which, of course, is a'definite disadvantage which tends seriously to restricttheir usefulness.

I have now discovered,however, that artificial filamentary materials having a basis of cellulose acetate or other organic derivative of cellulose, and particularly filaments in staple fiber form, may be treated so as to impart a substantially permanent crimped or crinkled structure thereto. In accordance with the novel process of my invention, filamentary materials having a basis of cellulose acetate are immersedin a liquid medium having at least a softening action on'the cellulose acetate fi1am'ents,"and, after the excess liquid-is 7 Claims. (Cl. 8-431) character of the filaments removed from the filaments, they are then immersed in water at an elevated temperature. The

filaments are maintained in the Water bath for a short time after which the Water is removed and the treated filaments are dried with heated air. This treatment effects a marked change'in the In place of their originally smooth and straight structure, .the filaments are 'now permanently crimped or crinkled and possess a full and elastic hand substantially similar to that possessed by wool. Furthermore, the filaments are far more resilient than prior .to treatment and recover their original voluminous structure even after the prolonged application of action on the cellulose acetate filaments may be employed. Examples of such liquids are aqueous solutions of ethyl alcohol, containing from to 95.5% of the alcohol, aqueous, solutions of acetone containing from 20 to of acetone, and aqueous solutions of acetone containing ethyl and/or methyl alcohol, for example, those solutions containing from 10% to 40% of acetone and from 10 to 50% of ethyl and/or methyl alcohol. Solutionscontaining ethyl alcohol, acetone or methyl alcohol together with organic liquids which do not exert any softeningor swelling action on the cellulose acetate filaments such as benzol andtoluol, xylol or. paraffinichydrocarbons may also be employed. Preferably, We employ aqueous solutions of ethyl alcohol containing from 7.0 to by volume of the alcoholas the. treating medium. The alcoholic solutions may beat a temperature of from 65 to F. during treatment and the filaments may be maintained therein for from 5 to 60 seconds. When employing aqueous solutions of ethyl alcohol, the temperature is preferably about 90F. and the filaments are usually maintained therein for about 30 seconds. Following this treatment, the excess liquid is removed in any convenient manner, such as, for examplecentrifuging. v

The moist filaments are removed from the centrifuge after the solvent treatment and are then placed in a water bath at a temperature of 60 to 212 F.", preferably about to F. for 1 to 5 seconds. Atthefend of this period the filaments are removed from the water bath, centrifuged I drying is suitable. The filaments may be dried,

for example; by being placed upon screens or racks and entered into a chamber through which hot air is 'circulated,'or the filamentsmay be.

placed in a rotary drier in which they are tumbled about while hot air passes therethrough. During the drying operation, the air may be at a temperature of 68 to 300 F.

The filaments may be treated while in a continuous filamentary form but preferably they are converted into relatively short staplelengths, for example from 3 to 6 inches in length, beforebeing. treated.

The filaments may be prepared in any con-- venient manner well known to the art suchas by dry-spinning or wet-spinning operations; Preferably, we employ filamentshav-ing; a basis of an. organic derivative of cellulose which. are prepared by dry-spinning operations. A particularly valuable product is obtained when I employ those dryspun filaments which are not subjected to any tension or draw-down during the spinning operation as, for example, those filaments prepared" in accordance with the process of U. S. Patent No. 2,290,929. The filaments; may be. of; any convenient; denier; excellent results being achieved with filamentsiof 1.5 to 30 denien;

In. order further to illustrate my invention but Without being limited. thereto, the following ex.- ample is given.

Example Cellulose acetate.- filaments. are: dry-spun with.- out. tension or: draw-down. employing. a' solution of cellulose acetate. in acetone containing: about 25 by weight oiicellulose; acetate. and: 7 by weight of 95/5 acetone/water; The filaments. are spun so as.to. be. approximately 6 denier per filament". The continuous filaments are then cut into staple fiber' in any convenient manner in which the fibersarefrom 3.to. Binchesinl'ength.

After being suitably opened and loosened up, the fibers, in the form of a bundle, are dipped into a solution containing 80% by volume of completelydenatured ethanol and 20% by volume of water, maintained at 90 F., for 30 seconds; The treated fibers are removed from thesolution and theexcess liquid is removed.- by centrifuging. From the. centrifugethe. fibers are placed in a water bath at atemperature of 1-5'0- to 1 60 FL and held therein for about 5 seconds. After being removed from the water bath, the fibers are centrifuged againto remove as much Water as possible; and are dried ina rotary drier with air at about 200 F; The staple fiber treated in 'thi's manner" is observed to have lost the soft and typical handof cellulose acetate" fibers and now possesses aharsh, voluminous andresilient hand greatly resemblin that of" wool; Thefibersare substantially permanently crimped andeven' after bein subjected to an appreciable pressure fora considerable period of time,,.the fibers resume their. original lofty character and form when the. pressure isremoved.

While. our invention. hasbeenmore particularly described in connection with the. treatment of artificial filaments. having, a.v basis. of cellulose acetate, it may be. employed in connection with thetreatment. ofI filaments haying ab'asisoflotherl organic. derivatives of. cellulose. for example, cela Iul'ose, esters such as. cellulose, propionate and. collulose. butyrate, mixed esters such as. cellulose acetate-propionate and cellulose. acetateebutyrate, and cellulose ethers. such as ethyl cellulose andbenzyl cellulose.

It is to be understood that. the foregoing de.-

therein without departing from the spirit of my invention.

The expression swelling agent as employed in the appended claims is to be construed as including within its scope substances which not only have a swelling effect on the organic derivative of cellulose but which may also have a, solvent action thereon.

Having described my invention, what I desire to secure by Letters Patent is:

1. Process for the production of voluminous, permanently crimped artificial staple fibers, which comprises. immersing relaxed, unstretched andv una-ssocratedv dry-spun staple fibers, having a basis of arr. organic derivative of cellulose and prepared. from filaments spun without any tension being exerted thereon, in an aqueous liquid medium containing a water-soluble swelling agent having at least a softening action on the organic derivative of cellulose, removing excess liquid from the. staple fibers, immersing. thevstaple. fibers inv water at atemperature of about. 150 to 1 60 B1,, removing the water from the staple: fibers and drying the staple. fibers, whereby voluminous, permanently crimped staple. fibers are produced.

2. Process for the production of voluminous, permanently crimped. artificial. staple. fibers, which. comprises immersing relaxed, unstretched and unassociated dry-spun staple fibers, having a basis of cellulose. acetate. and prepared from filaments spun without any tension. being exerted. thereon, in. an. aqueous liquid. medium. containing a water-soluble swellingv agent having at. least a. softening. action. on. the celluloseace.- tate, removing. excess. liquid from the staplefibers, immersing the. staple. fibers in water at a. temperature of about. 150. to. 160? F., removing; the water from the staple fibers and drying thestaple fibers; whereby voluminous, permanently crimped staple fibers are. produced;

3. Process for, the production of. voluminous; permanently crimped artificialstaple; fibers; which comprises immersing relaxed, unstre-tched and. unassociatedl dry-spun staple: fibers, having a basis of. cellulose. acetate. and prepared. from filaments. spun. without. any tension being. exerted thereon, containing from 70 to by volume of ethyl alcohol, removing excess liquid from the staple fibers,v immersing the staple fibers in water at. a. temperature. ofv about 150. to 160 F., removing; the water from the staple fibers and drying. the staple fibers, whereby voluminous; permanently crimped staplev fibers are produced.

4. Process. for the production of voluminous; permanently crimped artificial; staple fibers; which. comprises: immersing, relaxed, unstretchecl and unassociated. dry-spun. staple. fibers, having a basis. of; cellulose acetate andprepared: from filaments spun with-outrany tension bein exerted thereon, containing from 7.0 to 90% volume of. ethyl alcohol for from. 5. to 60 seconds, removing excess.- liquid: from the. staple fibers; immersing the staplefibers in water at.-.a'- tempe1rature of about 139 1.60% forfroirr 1 to: 5 seconds,. removing. the. water from the. staple fibers: anddry-ing the staplefi bers whereby; vole uminous, permanently crimped staple fibers. are

produced. I

5-. Process. for: theproduction 0st voluminous; permanently crimped; artificial. staple: fibers; which. comprises immersing, relaxed unstretched andunassociated' dry-spurt staple fibers, having a basis of cellulose acetate-.- and prepared from filaments. spunwithout any tension being: exerted thereon, containing from 7-0: to 90% by volume of ethyl alcohol fr from to .60 seconds at a temperature or to 110 F., removing excess liquid from the staple fibers, immersing the staple fibers Water at a temperature of about 150 to 160 FylfOI' from 1 to 5 seconds, removing the water from the staple fibers and drying the staple fibers, whereby voluminous, permanently crimped staple'fibrs are produced.

6. Process forth'e production of voluminous,

permanently crimped artificial staple fibers;

which comprises immersing relaxed, unstretched and unassociated dry-spun staple fibers, having a basis of cellulose acetate and prepared from the staple fibers and drying the staple fibers,

, fibers .are produced.

whereby voluminous, permanently crimped staple '7.*Process for the production of voluminou permanently crimped artificial staple fibers, which comprises immersing relaxed, unstretched and unassociated dry-spun staple fibers, having a basis of cellulose acetate and prepared from filaments spun iwithout any tension being exerted thereon, containing by volume of. ethyl alcohol for about 30 seconds at a temperature of F., removing excess liquid from the staple fibers, immersing the staple fibers in water at a temperature of about to F. for about 5 seconds, removing the water from the staple fibers and drying the staple fibers, whereby voluminous, permanently crimped staple fibers are produced. a

' FREDERICK G. DODGE. 

